Engine

ABSTRACT

A rotary fluid engine powered by externally pressurized working fluid including a rotor and externally plurality of swinging arms positioned to engage with and impart a torque force to the rotor when the arms are driven sequentially inward by the selective admission of charges of externally pressurized working fluid. A first segment on the rotor surface engages the free end of each arm as the arm is driven inwardly and a second segment on the rotor surface operates to return the arm outwardly after the power impulse is completed. Valving and conduit means are provided to control the direction of the working fluid to the arms and exhaust means are provided to exhaust spent working fluid from the engine. In one embodiment, the valving and conduit means are adapted to direct charges of externally pressurized working fluid sequentially against said arms so that the engine operates as a simple engine. In a second embodiment, the valving and conduit means are adapted to direct charges of externally, pressurized working fluid first against one of said arms at a high pressure and secondly against another arm at a relatively lower pressure so that said engine operates as a compound engine. In a third embodiment, transfer valve means are provided which permit said engine to be switchable between said simple and compound modes of operation. The rotor surface may include a plurality of said first and second segments so that each arm will transmit a corresponding plurality of power impulses to the rotor for each complete rotor revolution.

inckley Dec. 9, 1975 ENGINE [76] Inventor: John N. Hinckley, Tree Top Apts.,

Apt. 111, 10522 Santa Gertrudes, Whittier, Calif. 90603 [22] Filed: Nov. 30, 1973 [21] Appl. No.: 420,746

Related US. Application Data [52] US. Cl. 418/8; 418/12; 418/249 [51] Int. GL 1 01C l/00; FOlC 13/00; F04C 13/00 [58] Field of Search 418/8, 12, 139, 249251; 60/39.61

[56] References Cited UNITED STATES PATENTS l/1872 Faucett ..4l8/250 5/1903 Taylor ..4l8/249 917,436 4/1909 418/249 992,673 5/1911 418/249 1,172,505 2/1916 Cauwenbergh... 418/250 1,616,333 2/1927 Prince 418/249 3,174,274 3/1965 Frye 418/141 3,289,652 12/1966 Muller 418/249 FOREIGN PATENTS OR APPLICATIONS 54,977 l/1891 Germany 418/249 Primary Examiner-John J. Vrablik Attorney, Agent, or Firm-Melvin F. Jager A rotary fluid engine powered by externally pressurized working fluid including a rotor and externally plurality of swinging arms positioned to engage with and impart a torque force to the rotor when the arms are driven sequentially inward by the selective admission of charges of externally pressurized working fluid. A first segment on the rotor surface engages the free end of each arm as the arm is driven inwardly and a second segment on the rotor surface operates to return the arm outwardly after the power impulse is completed. Valving and conduit means are provided to control the direction of the working fluid to the arms and exhaust means are provided to exhaust spent working fluid from the engine. In one embodiment, the valving and conduit means are adapted to direct charges of externally pressurized working fluid sequentially against said arms so that the engine operates as a simple engine. In a second embodiment, the valving and conduit means are adapted to direct charges of externally, pressurized working fluid first against one of said arms at a high pressure and secondly against another arm at a relatively lower pressure so that said engine operates as a compound engine. In a third embodiment, transfer valve means are provided which permit said engine to be switchable between said simple and compound modes of operation. The rotor surface may include a plurality of said first and second segments so that each arm will transmit a corresponding plurality of power impulses to the rotor for each complete rotor revolution.

17 Claims, 18 Drawing Figures US. Patent Dec. 9 1975 Sheet 1 of9 3,924,976

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US. Patent Dec. 9, 1975 Sheet 3 of9 3,924,976

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US. Patent Dec. 9, 1975 Sheet 5 of9 3,924,976

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FIG. IIC

US. Patent Dec. 9, 1975 Sheet 8 of9 3,924,976

ENGINE This application is a division of my application Ser. No. 274,202 filed July 24, 1972. now US. Pat. No 3,824,044 which in turn is a division of my application Ser. No. 860,684, filed Sept. 24, 1969, now U.S. Pat. No. 3,684,413, issued Aug. 15, 1972, which is a continuation-in-part of my application Ser. No. 8l2,656, filed Apr. 3. 1969, entitled Engine now abandoned and assigned to the same assignee as the present invention.

The present invention relates to an improved prime mover and more particularly relates to an improved rotary engine which is powered by externally pressurized working fluid and is capable of replacing or supplementing conventional reciprocating piston internal combustion engines.

As well-known in those skilled in the art, the internal combustion engine in current use has many inherent disadvantages which have caused considerable concern about the continued use of that type of an engine as the dominant prime mover. For instance, two principal disadvantages of internal combustion reciprocating piston engines are low thermal efficiency and poor pollutant emission characteristics. These disadvantages result mainly from the inability of the engine to utilize the fuel effectively or to complete the combustion of the fuel within the expansion chamber of the engine before exhausting the spent fuel to the atmosphere. Another disadvantage of reciprocating piston engines in current use is inherently low overall mechanical efficiency. It is well-known, for instance, that the overall efficiency of piston engines is suppressed to approximately 25% by such factors as the inability of the pistons to produce power for about the first 30 and last 40 of each stroke, and the need for power-absorbing static and dynamic counterbalancing, and parasitic auxiliary systems.

Many attempts have been made to improve upon the thermal characteristics of reciprocating piston engines. These attempts have included such efforts as major engine redesign to increase the fuel combustion during expansion, and suppression of exhaust emissions with parasitic equipment, such as regenerators and the like. Despite the success of some of these efforts, most reciprocating engine designs continue to require expensive fuels and continue to have unacceptably high pollution characteristics. Efforts to improve the characteristics of reciprocating engines have also led to complicated designs which are expensive to manufacture, operate and maintain, and which continue to have an unsatisfactorily low mechanical efficiency.

The present invention overcomes the above-mentioned problems of reciprocating piston engines by providing a rotary engine which is powered by externally pressurized working fluid and is capable of operating with substantially improved mechanical and thermal efficiencies and substantially improved anti-pollution characteristics. The rotary engine of the present invention also has a high horsepower-to-weight ratio and can produce high torque with a smooth and continuous flow of power to the output shaft. The structural and functional characteristics of this improved rotary engine also permit great flexibility of operation, thereby allowing the engine to be adapted for a variety of applications.

The rotary engine is adapted for use in a power sys tem having a continuous source of working fluid and means for pressurizing the working fluid outside of the engine. The system also includes means for feeding charges of such externally pressurized working fluid into the engine so that the pressurized fluid expands in the engine and creates a torque force which drives the engine output shaft. The externally pressurized working fluid may comprise a compressed gas such as compressed carbon dioxide, in which case the power system is provided with means for maintaining the gas under pressure. Alternatively, the externally pressurized working fluid may be pressurized vapor such as superheated steam, and the power system provided with an external heat source, such as a boiler, for creating the pressurized vapor. Similarly, the power system including the engine may use an open fluid cycle wherein the working fluid is exhausted to the atmosphere after expansion in the engine, or may use a closed fluid cycle which recirculates the working fluid through the system.

EXEMPLARY EMBODIMENTS Additional objects and features of the present invention will become apparent from the following description of several exemplary embodiments. In the illustrated embodiments, the engine is adapted as a Ran kine cycle engine having a closed fluid system wherein energy is added to the pressurized working fluid by the application of external heat. Superheated steam is the preferred working fluid for the illustrated system, but it will be appreciated by those skilled in the art that alternative working fluids such as mercury or organic compounds reduced to vapor can be utilized with equal effectiveness in such a vapor cycle system. In some of the illustrated embodiments, the engine rotor is provided with a single lobe, and the engine is adapted so that each arm transmits one power impulse to the rotor for each rotor revolution. In other illustrated embodiments, the engine rotor is provided with double opposed lobes, and the engine is adapted so that each arm transmits two power impulses to the rotor for each rotor revolution.

The standard components of the Rankine cycle system, such as the fluid reservoir, the vapor generator for creating the externally pressurized working fluid, the condenser, valves, pumps and heaters, have been excluded from the disclosure for purposes of simplicity. The operation of such components to create the pressurized working fluid, such as by converting water vapor to superheated steam by the application of external heat, and to circulate the working fluid to and from the engine are well-known and therefore need not be described in detail.

In the drawings:

FIG. 1 is a partial cross-sectional view of a simple external combustion engine in accordance with this invention embodying a sin gle-lobe rotor, as viewed along the line 1-1 in FIG. 2;

FIG. 2 is a partial cross-sectional view of the simple external combustion engine illustrated in FIG. 1, as viewed from a plane parallel to the output shaft;

FIG. 3 is a partial cross-sectional view of a compound external combustion engine in accordance with this invention embodying a sin gle-lobe rotor, as viewed along the line 33 in FIG. 4;

FIG. 4 is a partial cross-sectional view of the compound external combustion engine illustrated in FIG. 3 as viewed from a plane parallel to the output shaft;

FIG. 5 is a schematic end view of a valve housing for the compound engine which is adapted to transfer the pressurized working fluid from one engine expansion chamber to another expansion chamber;

FIG. 6 is a schematic view illustrating the flow of working fluid through the compound engine;

FIG 7 is a schematic end view of a valve housing adapted for use with the compound engine illustrated in FIGS. 3 and 4 which modifies the engine to permit selective switching between the simple and compound modes of operation;

FIG. 8 is a schematic view illustrating the switchable engine operating as a simple external combustion engine, and further illustrating the valving and manifold system which permits the engine to be switched between a compound and simple mode of operation;

FIG. 9 is a partial cross-sectional end view of another embodiment of the engine in accordance with this invention incorporating a double-lobe rotor and six swinging arms which cooperate to form a balanced simple external combustion engine unit;

FIG. 10 is a cross-sectional side view of the simple engine illustrated in FIG. 13, as viewed along the line 1414 in FIG. 13;

FIGS. 1 IAJ) are removed partial sectional views of a suitable adjustable valve means for selectively controlling the admission and cutoff of the working fluid in the engine illustrated in FIGS. 13 and 14;

FIG. 12 is a partial cross-sectional end view of still another embodiment of the engine incorporating a double-lobe rotor and six swinging abutment arms which is adapted to be switchable between simple and compound modes of operation;

FIG. 13 is a cross-sectional side view of the switchable engine as viewed alone the line 1313 in FIG. 12;

FIG. 14 is a removed end view of the fluid transfer plate incorporated in the switchable engine illustrated in FIGS. 12 and 13;

FIG. 15 is an end view of the transfer plate shown in FIG. 14 schematically illustrating the relationship between the transfer plate and the cut-off valves of the engine assembly.

SINGLE-LOBE ROTOR FIGS. 1 and 2 illustrate an external combustion engine embodiment of the present invention having a single-lobe rotor which is adapted for a simple mode of operation, that is there is no compounding of expansion of the pressurized working fluid before the fluid is ex hausted from the engine. This simple engine is designed to utilize single charges of pressurized working fluid expanded in the engine for prolonged periods of time, such as throughout about 75 or 80 percent of the expansion period. As a result of this mode of operation, the engine has a high-torque output and is suitable for low-speed high-torque applications.

Referring to FIGS. 1 and 2 in more detail, the simple external combustion engine is generally indicated by the reference numeral 10. The engine 10 includes a rotor housing containing three pivoted swinging abutment arms 46A, 40B and 40C and a single-lobe power rotor 50. The arms 40A-C are pivotally mounted on pins 4lA-C (FIG. 1) and the rotor 50 is pivotally mounted on a central drive shaft 30. Such pivotal connections for the arms 40A-C and rotor 50 are accomplished by keys or splines and are free-floating connections which permit the arms and rotor to float laterally and maintain a position of equilibrium within the housing 20 during the operation of the engine.

As indicated in FIG. 1, the rotor housing 20 and the interior surfaces or top Walls of the arms 40A-C cooperate to define a generally cylindrical chamber within which the rotor 50 can rotate. Generally, during the operation of the engine a pressurized working fluid such as high pressure superheated steam is directed into the interior of the rotor housing 20 in a manner which forces the front end portion of the arms 40A-C sequentially inwardly against the surface of the rotor 50. The expanding working fluid works againstthe bottom walls of the arms 40A-C and the exposed surface of the rotor 50 to thereby impart a rotational driving force to the rotor, and the rotor in turn transmits an output to the drive shaft 30.

As seen in FIG. 2, one end of the rotor housing 20 is closed by a flywheel housing .60 and the other end is closed by a valve housing 70. The housings and 70 include centrally positioned main bearings 61 and 71, respectively, which support the drive shaft 30. The housings 60 and 70 also include machined end plates 62 and 72, respectively, which seal the adjacent ends of the rotor housing 20. Suitable head bolts and gasketing (not shown) are provided to assure that the plates 62 and 72 seal the rotor housing 20 effectively. The plates 62 and 72 also pivotally support the pivot pins 41AC (FIG. 1) about which the arms 40A-C pivot during the operation of the engine.

In addition, the housing 60 contains a flywheel 63 keyed to the drive shaft 30. In the illustrated single rotor embodiment, the flywheel is provided with sufficient counterweight to offset the weight of the rotor 50 and thereby maintain the dynamic balance of the engine. The housing 60 also contains an accessory drive gear assembly comprising a gear 64 and pinion 65 for operating the engine accessories. A lubricator pump 66, driven by the pinion 65, is connected to a sequentially-metered lubrication system (not shown) which meters the necessary amount of lubricating oil to each surface such as the bearings 61 and 71 requiring lubrication. Inspection plates 67 and 68 are also provided on the flywheel housing 60 to permit access to the interior of the housing for inspection and repair.

As shown in FIG. 2, the rotor 50 and arms 40A-C of the engine in accordance with this invention are closely machined to have approximately the same width as the rotor housing 20. This design provides for a large surface area on the rotor 50 and arms 40A-C for contact with the working fluid during the operation of the engine. Moreover, by this arrangement the rotor and arms are positioned in the housing 20 and spaced from the plates 62 and 72 only be a close tolerance. Sealing means thus can be provided between the sides of the arms 40A-C and rotor 50 and the plates 72 and 62 to prevent leakage of any working fluid past the rotor or arms.

In the preferred embodiment of the invention, labyrinth sealing is used to seal the sides of the rotor 50 and arms 40A-C with respect to the end plates 62 and 72. Such labyrinth sealing eliminates the need for lubricating moving parts such as piston rings or seals and is accomplished by providing a series of short labyrinth grooves 52 on the sides of the rotor 50 and similar grooves 42 on the sides of each of the arms 40AC. The grooves 42 and 52 are arranged to follow the profile of the associated arms or rotor so that each groove acts as a check valve to stop the flow of working fluid past the arms or rotor in the clearance adjacent the plates 62 and 72. The short labyrinth grooves 42 and 52 also prevent the working fluid from traveling along the full length of the rotor or arms. The above-described freefloating connections for the arms 40AC and rotor 50 assist the sealing function of the labyrinth grooves 42 and 52 by allowing the arms and rotor to be self-centering within the housing 20. The effectiveness of the labyrinth grooves 42 and 52 is further assisted by designing the rotor 50, arms 40A-C and housing 20 so as to have substantially equal coefficients of expansion. The clearance between the plates 62 and 72 and the rotor and arms therefore will be substantially constant regardless of the engine load or operating temperature.

As illustrated in FIG. 1, the free end of each of the arms 40AC includes a bevelled portion 43 which allows the associated arm to engage with the rotor 50 along a flat and highly machined contact surface. This substantial contact surface 'on the arms 40A-C is held against the rotor 50 by the force of the expanding working fluid and is sufficient to prevent any substantial leakage between the arms and rotor. The bevelled portion 43 also allows the rotor and arms to withstand a high loading force by distributing the force of the expanding working fluid over a large area of contact on the arms and rotor.

Each arm 40A-C has a projection 46 on its inner surface which defines the point closest to the associated pivot pin 41A-C at which the rotor will engage with the arm. Such an arrangement assures that the forces of the rotor 50 will act on the arms 40A-C at a point of substantial leverage. A relief 47 is provided on each arm 40A-C to allow clearance for the rise 57 of the rotor to pass by the arms. Sealing strips 44 are provided to seal the arms 40A-C with respect to the rotor housing 20 adjacent the pivoted end of the arms, as shown in FIG. 1. The strips 44 thereby separate the expansion and exhaust phases of the working fluid during the operation of the engine.

The engine in accordance with this invention also is provided with a valving mechanism which admits the charges of pressurized working fluid into the rotor housing in the proper sequence. In the illustrated embodiment, for instance, the pressurized working fluid is admitted in a pattern which swings the arms 40A, 40B and 40C inward sequentially against the rotor 50, and drives the rotor 50 clockwise in FIG. 1. To achieve such control of the working fluid, the valve housing 70 contains fluid admission chests 74AC, one of which is associated with each of the arms 4OA-C.

Each admission chest 74AC is connected to a vapor generator (not shown) or another suitable source of high pressure fluid by means of intake pipes 75. As shown in FIG. 2, the chests 74AC also are in fluid communication with an expandable chamber defined by the rotor housing 20 and the associated arm 40A-C through intake manifolds 76 provided in the valve housing 70 and through aligned intake chambers 22 provided in the rotor housing 20. The intake chambers 22 are spaced within the housing 20 (FIG. 1) so that the pressurized working fluid enters the rotor chamber at a location closely adjacent the free end of the associated arms 40A-C. By this arrangement, the entering charge of fluid initially contacts the associated arm at a point of great leverage and is capable of forcefully swinging the arms inwardly against the rotor 50. As seen in FIG. 1, the free end of the arms 40A-C seal the 6 associated intake chamber 22 closed when the arm is in the outermost position.

The valve housing also contains a valve mechanism for controlling the timing and rate at which the pressurized working fluid is admitted into the chests 74AC. To accq plish such timing and metering, each of the chests 74AC is separated from the associated intake manifold 76 by a poppet valve 77. The stroke of each poppet valve 77 is controlled by cams 78 provided on the drive shaft 30. A conventional gearing mechanism 79, such as the Stephenson mechanism illustrated schematically in FIG. 2, connects the valves 77 to the cams 78 and permits the closing stroke of the valves 77 to be adjusted to vary the rate or quantity of working fluid supplied to the engine. As well-known to those skilled in the art, such a variable cutoff mechanism can be operated either manually or automatically to vary the operating characteristics or the performance of the engine 10. A cover plate 80 closes the valve housing 70 and protects the above-described valve mechanism from damage.

The engine 10 also includes an exhaust system for discharging the spent working fluid from the expandable chamber defined by the rotor housing 20 and each arm 40AC. In this regard, the valve housing 70 is provided with a plurality of exhaust manifolds 92 which are spaced uniformly about the housing to receive the spent working fluid from the three segments of the engine 10. In addition, the end plates 62 and 72 of the housings 60 and 70 are provided with uniformly spaced exhaust ports A-C. As indicated in FIG. 1, an exhaust port 90 is positioned near the pivoted end of each of the adjacent arms 40A-C. Each port 90 is in fluid communication with the adjacent exhaust manifold 92 and can thereby operate to discharge the working fluid from the expandable chamber associated with the preceding arms. The fluid is thereby exhausted into a suitable condenser or the like, from which the fluid is fed to a vapor generator and re-pressurized for recirculation through the engine.

The ports 90A-C are designed to be sufficiently large to permit rapid exhaustion of the spent working fluid with a minimum loss of energy. Further, the ports 90A-C are positioned to permit the power impulses on the rotor 50 to overlap, so taht the operation of the engine 10 is smooth and the application of torque to the rotor 50 is continuous.

To eliminate the need for auxiliary exhaust valve mechanisms, the engine 10 includes valving portions 45A-C, defined by the lower or rear end of each of the arms 40A-C, to control the opening and closing of the associated exhaust ports 90AC. As illustrated in FIG. 1, the valving portions 45A-C extend beyond the arm pivot pins 4lA-C to cover the adjacent exhaust port 90A-C when the associated arm is in its outermost position (See arm 408, FIG. 1). The valving portions 45A-C swing away to open the ports 90AC when the associated arm 40A-C swings into its innermost position (See arm 40C, FIG. 1). The valving portions 45A-C are designed so that the opening and closing of the exhaust ports 90A-C are coordinated with the positioning of the arms 40AC and the rotor 50 during the operation of the engine 10.

The rotor housing 20 has recesses 25 to receive the valving portions 45A-C as the arms 40AC move inwardly toward the rotor 50. The sealing strips 44 frictionally engage with the associated arm and prevent the pressurized working fluid from becoming trapped within the recess 25. The recesses 25 preferably are vented to the atmosphere by suitable means (not shown) so that any working fluid which may enter the recesses is exhausted without inhibiting the action of the associated arm.

In the preferred embodiment of this invention, the rotor 50 is adapted to control the sequence of movement of the arms 40A-C to overlap the power impulses transmitted to the rotor so that the flow of power to the rotor 50 is smooth and continuous. The rotor 50 also controls the inward and outward movement of the arms so taht the swinging motion of each arm closely approximates a simple harmonic motion. Such arm movement minimizes the amount of energy absorbed by inertia losses resulting from the rapid reversal of the arms.

The surface of the rotor 50 is designed to engage with the bevelled portions 43 of the arms 40A-C to receive a power impulse from the arms and to control the sequential movement of the arms during the operation of the engine. To accomplish these functions, the rotor 50 includes a nose or high point 53 positioned to engage with the adjacent arm 40AC and maintain the arm in its outermost position for a selected time period (See arm 40B, FIG. 1). Further, the surface of the rotor 50 defines a fall segment 54 which is engaged by the arms 40A-C s the arms are driven inwardly by the force of the working fluid (See arm 40A, FIG. 1). The fall segment 54 has a configuration which causes the arms 40A-C to move inwardly with approximately simple harmonic motion. The arm fall segment 54 terminates with a sloping portion 55 which decelerates the inwardly moving arm and prepares the arm for a reversal of direction.

The sloping portion 55 leads the inwardly moving arm 40A-C to a low dwell segment 56 on the surface of the rotor 50. The low dwell segment 56 is concentric to the axis of rotation of the rotor 50 and extends along the rotor surface for a selected number of degrees. The dwell segment 56 thereby stops the inward movement of the arms 40A-C and defines the limit for inward arm travel.

Since the three arms 40A-C in the illustrated engine are spaced 120 apart, the cycle of operation for the arms will be 120 out-of-phase, and the movement of adjacent arms will be separated by 120 of rotor rotation. Thus, each of the arms 40A-C will complete its inward movement, and traverse the fall segment 54 from the high point 53 to the low dwell segment 56, as the rotor 50 rotates through 120. However, in the preferred arrangement the fall segment 54 is designed to complete the inward movement of the arms 40A-C as the rotor rotates for less than 120, for instance 1 10. This arrangement allows the arms to decelerate smoothly and assures that the stroke of one arm, such as arm 40A, is completed before the exhaust cycle is started by movement of the adjacent arm.

The movement of the adjacent arm (arm 40B) will start after 120 of rotation of the rotor 50, but the valving portion 45 of the arm and the associated exhaust port 90 are arranged so that exhaust does not start until that arm moves through a small arc, such as l-20. This design permits an overlapping of the power impulses, to obtain optimum torque on the rotor 50, by preventing the exhaust ports 90 from opening prematurely.

The overlapping of the power impulses on the rotor 50 is assisted by designing the low dwell segment 56 of the rotor 50 with an arc of to so that the arms 40A-C contact the segment for a short time after the rotor has rotated beyond 120. The dwell segment 56 thereby precludes outward movement of the engaged arm 40 until after the power strokes of the adjacent arms (e.g., 40A and 40B) have overlapped and the associated exhaust port has opened. This arrangement of the dwell segment 56 also allows the working fluid to expand fully against the inwardly moving arm 40 and rotor 50 before the arm starts to move outward and force the fluid into the exhaust system.

The next segment of the rotor 50 which engages with the arms 40A-C is a rise segment 57 which is designed to force the engaged arm outwardly from its innermost position (See arm 40C, FIG. 1) toward its outermost position (See arm 40B, FIG. 1) with simple harmonic motion. The rise segment 58 preferably is designed to drive the arms 40A-C outwardly as the rotor 50 rotates through approximately 90 additional degrees.

The remaining surface of the rotor 50 between the rise segment 57 and the high point 53 comprises a high dwell segment 58. This segment 58 is concentric with the axis of the rotation of the rotor 50, and is designed tomaintain the adjacent arm 40 in its outermost position (See arm 40B) through approximately 140 of rotation of the rotor 50. The rotor 50 then has rotated 360 with respect to the arms 40, and is in a position to repeat its operating cycle. The above-described rotor segments thereby provide the rotor 50 with a single lobe, having a high point 53 which allows each arm 40A-C to complete its cycle of movement once for each revolution of the rotor. By this arrangement, each arm 40A-C will transmit one power impulse to the rotor 50 per rotor revolution.

In operation, the swinging arms 40A-C transmit torque to the rotor 50 in proportion to the force imposed upon the outward sides of the arms by the pressurized working fluid. The rotor 50 and arms 40A-C further act to seal the fluid expanding in one segment of the engine 10 from the fluid exhausting from another engine segment. This functional interrelationship between the arms 40 and the rotor 50 will be understood from a description of the operation of the engine through 1 complete cycle. Since the engine 10 consists of three symmetrical segments, each including one of the arms 40A-C, the cycle could start with any one arm. For purposes of illustration, the operation of the engine will be described with reference to a cycle initiated by admitting a charge of steam through the steam chest 74A to act upon the arm 40A.

To begin the engine operation, the valve gear mechanism 79 is adjusted, either manually or automatically, to introduce a charge of steam through the chest 74A at the desired rate. The mechanism 79 can be varied to cut off the steam charge after the rotor 50 rotates through a few degrees or' after the maximum of rotor rotation. As well-known by those skilled in the art, a longer cutoff time introduces a greater quantity of working fluid into the rotor chamber and increases the power output of the engine.

The valve mechanism 79 and the rotor 50 are timed so that the steam is admitted through the chest 7 4A and the associated channel 22 as the high point 53 of the rotor 50 passes the bevelled portion 43 on the free end of the arm 40A. The entering steam expands against the arm 40A and the rotor 50 and forcefully drives the arm 40A inwardly against the rotor. The expanding steam thereby imparts a torque force to the rotor 50, and drives the rotor and the shaft 30 (in a clockwise di- 9 rection in FIG. 1 As seen in FIG. 1, the engagement of the rotor 50 with the arms 40A and 40B seals the resulting expandable steam chamber (the increased volume below arm 40A) from the remaining portion of the rotor chamber.

In the illustrated engine 10, the fall segment 54 on the rotor 50 allows the arm 40A to move inwardly as the rotor 50 rotates through approximately 1 10. The motion of the arm 40A is then decelerated by the rotor sloping portion 55. The inward motion of the arm 40A is finally stopped when the arm engages the low dwell segment 56. In this embodiment, the arm 40A remains engaged with the segment 56 and remains in its innermost position until the rotor 50 rotates an additional degrees, or through a total are of 130.

Simultaneous with the above-described operation, the valve mechanism 79 operates to admit a second charge of superheated steam to the chest 74B and into the expandable chamber defined between the second arm 40B and the rotor housing 20. When the rotor 50 has traveled through 120 and thereby moved the rotor high point 53 past the bevelled portion 43 on the arm 403, the second charge of steam forces the arm 40B inwardly against the rotor. By this arrangement, a second power impulse begins against the rotor 50 at 120 of rotor rotation. Furthermore, the valving portion 45B on the arm 40B and the associated exhaust port 903 are designed so that the port 908 is not opened until the rotor 50 has moved 10 degrees beyond the free end of the arm 403. Thus, the first steam charge in the expandable chamber associated with the preceding arms 40A continues to expand and impart a torque to the rotor for this additional 10, and overlaps with the force of the second steam charge during that interval.

In the illustrated engine 10, the first arm 40A engages the rotor rise segment 57 after 130 of rotor rotation. Continued rotation of the rotor through 90 drives the first arm 40A outwardly and permits the second arm 403 to be forced inwardly. The outwardly moving arm 40A will thereby scavenge the first charge of steam and discharge the steam through the enlarging exhaust port 903. Further rotation of the rotor 50 through the remaining 140 degrees brings the high dwell segment 58 into engagement with the arm 40A. The arm 40A is thereby maintained in its outermost position while the cycle for the second arm 40B is being completed.

The same cycle of operation as described above for the arm 40A is followed by the arm 40C. It will be readily understood, however, that the cycle for the third arm 40C follows the cycle of arm 408 by 120, and leads the cycle for arm 40A by the same amount. 7 To illustrate the high torque characteristics of the simple engine 10 in accordance with this invention, various engine operating parameters were fed into a computer which was programed to calculate the expected performance of an engine having a rotor chamber with a four inch width and a 7.5 inch internal diameter and having the single-lobe rotor shaped as generally shown in FIGS. 1 and 2. In one computer example, the incoming steam pressure was selected as 200 psi gauge pressure and the steam cutoff was selected to occur in each segment of the engine after the rotor had traveled through 110. The steam was allowed to expand through 130 of rotor rotation to provide an overlap in the power impulses from the adjacent engine sections. The computerized data projected that under these conditions the steam pressure would drop to 179 psig after the steam is fully expanded through 130 and 10 would then be exhausted. The computerized data also projected that the mean output torque for the engine was 7,421 inch pounds, with a resultant power output of 141 indicated horsepower at 1,200 rpm.

In another computerized example, the same simple engine was analyzed with 200 psig steam being admitted with the cutoff adjusted to 55 of rotation of the to tor. In this example, the steam was allowed to expand for an additional of rotor rotation and was finally exhausted at a pressure of 72 psig. The projected characteristics for this engine were a mean output torque of 5,815 inch pounds, with a resultant power output of 111 indicated horsepower at 1,200 rpm.

Similar computerized data also established that the power output of the engine in accordance with this invention is directly proportional to the rotor width and speed, and the pressure of the incoming charge of ex ternal working fluid. If any of these parameters are doubled, for instance, the resulting power output of the engine also will be substantially doubled. Thus, the operating parameters or physical dimensions of the engine can be adjusted easily to adapt the engine to a particular application. It will also be appreciated that the shape of the single-lobe rotor 50 can be modified to adjust the operating characteristics of the engine to meet particular applications.

COMPOUND ENGINE SINGLE-LOBE ROTOR FIGS. 3 through 6 illustrate an external combustion engine having a single-lobe rotor which is adapted for a compound mode of operation. In this compound engine each charge of pressurized working fluid is expanded twice in the engine. Since each expansion of the pressurized fluid transmits torque to the rotor, the compound engine has excellent fuel economy and can operate at high speeds for a sustained period. The compound expansion of each charge of working fluid also minimizes the condensation of the fluid within the engine when the engine is operated with superheated steam.

Referring to FIGS. 36 in more detail, the compound external combustion engine includes many of the same components as the above-described simple engine 10. A rotor housing contains three pivoted swinging abutment arms A, 1403 and 140C, and a single-lobe power rotor 150. The arms 140A-C are pivotally mounted on pins 141A-C, and the rotor is mounted for rotation on a central drive shaft 130. The connections for the arms l40A-C and rotor 150 comprise keys or splines or the like which permit the arms and rotor to float freely in the lateral direction, and be self-centering within the housing 1.20. The rotor housing 120 and the interior surfaces of the arms 140A-C define a generally cylindrical chamber within which the rotor 150 will rotate during the operation of the compound engine 100.

As illustrated in FIG. 4, one end of the rotor housing 120 is closed by a flywheel housing and the other end is closed by a valve housing 170. The housings 160 and 170 include main bearings 161 and 171, respectively, and define end plates 162 and 172 which seal the adjacent ends of the rotor housing. The end plates 162 and 172 support the pivot pins 141AC (FIG. 3) about which the arms 140AC rotate. The housing 160 contains a counterweighted flywheel 163 which is keyed to the drive shaft 130. Accessory drive gears and pinions 164 and 165 are also provided in the housing 160 for driving the engine accessories, such as a lubricating 1 1 pump 166, in thewell-known manner. The housing 160 also includes removable inspection plates 167 and 168.

As shown in FIG. 4, the rotor 150 and the arms 140A-C of the engine 100 have approximately the same width as the rotor housing 120. This arrangement provides a large surface area on the rotor and arms for the contact with the working fluid, and spaces the rotor and arms within a very close tolerance to the end plates 162 and 172. The rotor and arms thereby can be sealed with respect to the end plates 162 and 172 by a plurality of short labyrinth grooves 142 and 152. As described above, the labyrinth grooves 142 and 152 follow the profile of the associated arm or rotor, and act as check valves to stop the flow of working fluid past the rotor and arms. The arms 140AC, rotor 150 and housing 120 are also designed to have substantially equal coefficients of expansion, so that the operation of the labyrinth sealing is unaffected by engine load or operating temperature.

As illustrated in FIGS. 3 and 6, each of the arms 140A-C includes a bevelled portion 143 at its free end for contacting the surface of the rotor 150. Each arm also includes projection 146 on its inner surface which prevents the rotor 150 from engaging with the arms at any point closer to the associated pivot pin 141A-C. The rotor 150 will thereby engage each arm 140AC at the high leverage section between the bevelled portion 143 and the projection 146. Each ann 140A-C also includes a relief 147 which provides clearance for the rise 157 of the rotor to pass by the arms. Further, sealing strips 144 are provided in the rotor housing 120 to engage with the adjacent arm 140A-C and seal the expansion chambers of the engine from each other and from exhaust chambers.

The lower end of each arm 140AC also defines exhaust valving portions 145A-C which move with the arms l40A-C and control the opening and closing of an associated exhaust port l90A-C. The exhaust ports 190A-C are cast in the face plates 162 and 172 of the gear housing 160 and the valve housing 170 and are connected to a fluid condenser or the like through exhaust manifolds 192. Recesses 125 receive the valving portions 145AC as the associated arm moves inwardly toward the rotor 150. The sealing strips 144 prevent the working fluid from becoming trapped within the recesses 125. The recesses 125 also are vented to the atmosphere by suitable means (not shown).

As illustrated by the position of the arm 140B in FIG. 3, the valving portions l45A-C are arranged to close the adjacent exhaust port 190AC when the associated arm is in its outermost position. The valving portions 145AC swing outwardly to open the adjacent port l90A-C when the associated arm swings into its innermost position. The operation of the exhaust ports 190A-C is controlled by the positioning of the arms 140A-C and the rotor 150.

Each of the arms 140A-C in the compound engine 100 also includes an outwardly projecting horn member 148. The horn member 148 are integral with the associated arm and are designed to extend outwardly from the arm for a distance which exceeds the length of the inward arm stroke. The horns 148 are formed adjacent the free end of the arms, and terminate to define a substantially flat contact surface 149 on the outer end of each arm. As clearly illustrated in FIG. 3, each horn 148 has outwardly converging side edges which give the horn an outwardly tapered or wedge-shaped configuration.

The rotor housing 120 is formed with a plurality of horn recesses 128 to accommodate the projecting horns 148. The recesses 128 also have a tapered shape which closely conforms to the shape of the horns 148 so that each recess will receive the adjacent horn when the associated arm 140A-C is in its outermost position (See arm 140B, FIG. 3). Further, as indicated by the arm 140C in FIG. 3, the horns 148 and recesses 128 are arcuate in shape so that the horns are in sealing engagement with the rotor housing 120 as the associated arm 140A-C moves inwardly toward the rotor 150. The ta pered shape of the horns 148, which provides the horns with a narrow width at their outer ends and a broader width at their inner ends, prevents the development of a partial vacuum in the horn recesses 128 with otherwise would inhibit the inward movement of the arms.

Since the extent of the horns 148 exceeds the length of the stroke of the arms lA-C, the horns will remain in sealing engagement with the rotor housing 120 throughout the operation of the engine. By this arrangement, the space in the recess 128 behind each arm l40A-C and the adjacent intake chamber122 define a closed chamber which expands in volume as the associated arm 140AC moves inwardly toward the rotor 150. In accordance with this invention, such chambers behind the arms 140A-C define high pressure chambers I-IP I-IP and I-IP respectively, which will receive a charge of working fluid at high pressure during operation of the compound engine 100.

In accordance with this invention, the engine 100 also is provided with low pressure chambers for receiving a charge of working fluid such as steam from each of the high pressure chambers HE to thereby compound the effect of the charge on the rotor 150. In the illustrated engine 100, the volume of the low pressure chambers LP, is approximately one and one half to two and one half times the volume of the associated high pressure chambers HP However, this ratio may be varied over a broad range by varying the design of the arms 140A-C and the rotor 150.

To provide the low pressure chambers, the rotor housing is cast to include uniformly spaced fluid channels 129. As shown in FIGS. 3 and 6, each channel 129 is positioned so that one end is in communication with the contact surface 149 on the adjacent arm A-C, and the other end is in communication with an intake chamber 173 east in the valve housing 170. By this arrangement, the working fluid expanding in the channel 129 will press against the adjacent surface 149 and urge the adjacent arm inwardly against the rotor 150. Further, as indicated by the arrangement of the arm 140A in FIGS. 3 ad 6, the rotor and adjacent arms define an expanding, sealed chamber which is in communication with the adjacent channel 129. Thus, each segment of the compound engine 100 is provided with an expanding low pressure chamber, designated respectively as chambers LP LP and LP which is sealed from the main portion of the rotor chamber by the adjacent arm 140A-C and the rotor 150, and sealed from the adjacent high pressure chamber HP A4 by the adjacent arm horn 148. In addition, as seen in FIG. 3 each of the low pressure chambers LP, is position adjacent one of the exhaust ports AC. The charge of working fluid therefore can be exhausted through the adjacent port 190 after the expansion of the fluid in the low pressure chamber is completed.

The engine 100 also includes a manifold and valving system for controlling the admission of the pressurized working fluid into the high pressure chambers HP and for transferring the fluid, after expansion in the high pressure chambers, to the low pressure chambers LP,, where the fluid is expanded further before being exhausted from the engine. In this regard, the valve housing 170 includes a plurality of admission chests I74AC which are arranged uniformly around the rotor 150. As shown in FIGS. 3 and 6, each chest 174A-C is in fluid communication with one of the high pressure chambers HP through a high pressure manifold 176 which is aligned with the intake chamber 122. Intake pipes 175 connect each manifold 176 with a vapor generator (now shown) or other suitable source of high pressure fluid.

Timing and metering of the incoming pressurized fluid is accomplished by separating the chests l74A-C from the associated intake manifold 176 by a poppet valve 177. The stroke from each valve 177 is controlled by cams 178 connected to the drive shaft 130 and by a Stephenson-type variable gearing mechanism 179. A cover plate 180 encloses the valve housing 170 to protect the abovedescribed valving and manifold system from damage.

As illustrated in FIGS. 5 and 6, the valve housing 170 also includes transfer channels 194A, 194B and 194C for transferring the working fluid from the high pressure chamber HP of one of the arms 140A-C to the low pressure chamber LP of the adjacent arm. More specifically, the transfer channel 194A extends across the housing 170 and connects the high pressure chamber I-IP directly to the low pressure chamber LP In a like manner, the channel 194B connects the high pressure chamber I-IP with the low pressure chamber LP and the channel 194C connects the high pressure chamber HP with the low pressure chamber LP In the preferred embodiment of this invention, no valving is needed between the high pressure chambers HP and the associated transfer channel 194A-C. The initial charge of working fluid entering the high pressure chambers will fill the transfer channels. Then, the motion of therotor 150 and arms 140A-C will control the transfer of the fluid charge through the channels from the high to the low pressure chambers, and the exhaust of the fluid from the low pressure chambers.

In the preferred embodiment wherein the compound engine is operated with steam or the like, the pressure chambers HP, and LP the transfer channels 194A-C the rotor 150 and the arms 140A-C are designed so that the change in volume of the low pressure chambers LP is at the same rate as the change in volume of the associated high pressure chamber HP. As a result, substantially no work will be done on the fluid during the transfer and there will be substantially no energy loss during the transfer phase of the engine operation. The alternative, if the thermodynamic characteristics of the working fluid require it, the fluid charge could be circulated through a suitable reheating system (not shown) or the like before the transfer through the channels 194A-C is completed.

The surface of the rotor 150 controls the movement of the arms 140A-C so that each arm swings with approximately simple harmonic motion, and the inertia losses resulting from the rapid reversal of the arms is minimized. In the preferred embodiment, the rotor 150 also controls the sequence for the arms 140A-C so that the power impulses transmitted to the rotor are overlapping.

Accordingly, the rotor 150 includes a high point 153 which will engage with the adjacent arm 140AC and maintain that arm in its outermost position for a selected period (See arm 140B, FIG. 3). An arm fall segment 154 on the rotor 150 engages the arms 140A-C as the arms are driven inwardly by the force of the working fluid (See arm 140A, FIG. 3). The fall segment 154 is shaped to move the arms inwardly with approximately simple harmonic motion, and terminates with a sloping portion 155 which decelerates the inwardly moving arm at the end of the power stroke. The sloping portion 155 leads the inwardly moving arm 140A-C to a low dwell segment 156 on the rotor 150. The low dwell segment 156, which defines the inner'limit for the arms 140A-C, is concentric to the axis of rotation of the rotor 150 and extends along the rotor for a selected number of degrees.

In the illustrated compound engine 100, where the arms 140A-C are uniformly spaced by 120 degrees, the movement of adjacent arms will be 120 degrees out-ofphase. Accordingly, each arm will complete its inward movement and transverse the fall segment 154 from the high point 153 to the low dwell segment 156, as the rotor 150 rotates through 120. In the preferred arrangement, the fall segment 154 is shaped to complete the inward stroke of each of the arms as the rotor rotates through an are slightly less than 120, such as 1 10. Such an arrangement decelerates the arm smoothly and allows the arm to rest against the low dwell segment 156 before the direction of movement of the arm is reversed.

The next segment of the rotor 150 to engage with the arms 140A-C is an arm rise segment 157. The rise segment 157 sequentially engages each of the arms 140A-C and forces the arm outwardly from its innermost position (See arm 140C, FIG. 3), toward its outermost position (See arm 140B, FIG. 3) with approximately simple harmonic movement. In the illustrated engine 100, the rise segment 157 is designed to complete the outward movement of the arms 140A-C as the rotor 150 rotates through approximately additional degrees.

Further, in the illustrated compound engine 100, the rise segment 157 and the fall segment 154 of the rotor 150 are arranged so that the movements of adjacent arms (e.g., arms 140A and 140B) transfer the working fluid from the high pressure chamber of one arm to the low pressure chamber of the adjacent arm without performing working on the fluid. To accomplish this, the rise segment 157 is designed to start the outward movement of one of the arms 140A-C immediately after the rotor has rotated through Since the 120 degree rotation of the rotor will allow the next arm to start its inward movement, this arrangement of the rise segment 157 causes the adjacent arms to start moving in opposite directions at approximately the same time. The change in volume of the associated high and low pressure chambers will thereby start simultaneously.

Segments 154 and 157 are thereby arranged so that the movement of the adjacent arms changes the volume in the associated high and low pressure chambers at the same rate. For example, the rotation of the rotor 150 will force the arm A outwardly and will permit the arm 140B to move inwardly so that the volume of the high pressure chamber HP decreases at the same rate as the volume of the low pressure chamber LP increases. The same relationship exists with respect to the other associated high and low pressure chambers.

The remaining surface of the rotor 150 between the rise segment I57 and the high point 153 comprises a high dwell segment 158. The dwell segment 158 is concentric with the axis of rotation of the rotor I50 and maintains the engaged arm 140 in its outermost position through approximately 170 of rotation of the rotor. The rotor 150 then has completed a 360 cycle with respect to each of the arms 140, and is in a position to repeat the engine operating cycle. The abovedescribed segments of the rotor 150 thereby provide the rotor with a single lobe, having a high point 153, which allows each arm 140A-C to complete, its cycle of movement and transmit one power inpulse to the rotor 150 for each rotor revolution.

Since the engine 100 consists of three symmetrical segments, each including one of the arms 140A-C, the operation of the engine can begin by introducing a charge of steam to any one of the high pressure chambers HP,, For purposes of illustration, the operation of the engine 1100 will be described with reference to a cycle initiated by admitting a charge of high pressure superheated steam through the chest 174A into the high pressure chamber HP where the steam will expand against the adjacent arm 140A.

The operation of the engine 100 is begun by adjusting the valve gear mechanism 179 to admit the high pressure steam charge through the chest 174A at the desired rate. The valve mechanism 179 can be set to cut off the steam after a few degrees of rotation of the rotor 150, or can be adjusted to admit steam for the full 120 of rotor rotation. The operation of the valve mechanism 179 is further timed so that the steam charge is admitted through the chest 147A and the associated steam channel 122 as the high point 153 of the rotor 150 passes the free end of the arm 140A (See FIG. 3).

The admitted high pressure steam charge expands in the chamber I-IP against the arm 140A and forcefully drives the arm 140A inwardly against the rotor. The expanding steam charge thereby imparts a torque force to the rotor 150 and the shaft 130 and drives the rotor and shaft in a clockwise direction as viewed in FIG. 3. The engagement between the rotor 150 and the bevelled edge 143 of the arm 140A seals the expansion chamber LP, from te remaining portions of the rotor chamber. The initial charge of steam also fills the transfer channel 194A (FIG. 5), but cannot enter the associated low pressure chamber LP because of the outward position of the arm 1403.

In the illustrated engine 100, the inward movement of the arm 140A continues as the rotor 150 rotates through approximately 1 The arm 140A then disengages from the arm fall segment 154 on the rotor and is decelerated by the rotor sloping portion 155. The inward motion of the arm 140A is stopped when the arm engages with the low dwell segment 156. Then, the low dwell segment 156 engages with the arm 140A until the rotor 150 has rotated 120, at which point the rise segment 157 engages the arm and forces the arm to move in an outward direction.

The rotation of the rotor 150 through 120 simultaneously moves the high point 153 on the rotor beyond the free end of the adjacent arm 14018, and permits the arm 1408 to start moving inward at the same time as the outward motion of arm 140A starts. Thus, the volume of the low pressure chamber LP starts to increase as the volume of the high pressure chamber HP decreases. The valve mechanism l79 is timed so that a charge of high pressure steam is admitted into the 16 chamber HP through the steam chest 1748 and expands against the arm 1408 as the arm is released by the rotor 150.

In accordance with this invention, the outward movement of the arm 140A forces the charge of high pressure steam which has expanded in the high pressure chamber I-IP through the transfer channel 194A (FIG. 5) and into the low pressure chamber LP,, of the adjacent armv 1408. Further, as set forth above, the outward movement of the arm 140A is coordinated with the in ward movement of the arm 140B so that the decrease in volume of the high pressure chamber I-IP occurs at the same rate as the increase in volume of the low pressure chamber LP By this arrangement the effect of a singlev charge of steam on the rotor 150 is compounded by allowing the steam to expand first in the chamber HR, at high pressure and then in the chamber LP at low pressure. During the second expansion, the steam operates against the contact surface 149 of the arm 1408 and adds to the force on the rotor created by the expansion of the charge of high pressure steam in the high pressure chamber I-IP Thus, the engine 100 more fully utilizes the energy of the working fluid.

As the operation of the engine 100 continues, the valve mechanism 179 admits a charge of high pressure steam into the high pressure chamber I-IP behind the next arm 140C. This steam charge causes the arm 140C to move inwardly against the rotor 150, as indicated in FIG. 3, as soon as the high point 153 on the rotor 150 passes the free end of the arm 140C. After the arm 140C has moved inwardly during 10 or 15 of rotor rotation, the associated exhaust port 190C begins to open. The 10 or 15 degree delay in opening of the exhaust port 190C assures that the impulses on the rotor 150 caused by the arm 140C will overlap the impulses from the arm 140B. As illustrated in FIG. 6, the charge of steam which has expanded for the second time in the low pressure chamber LP will then exhaust through the opened port 190C and be transmitted into a condenser or the like for recycling through the sytem.

The above-described cycle of operation for the arms 140A and 140B is repeated at intervals for each pair of adjacent arms. As a result, the cycles of the arms A-C are integrated and overlapping, and a continuous torque is transmitted to the rotor during the operation of the engine 100.

The integrated nature of the arm cycles is illustrated visually in FIG. 6. In FIG. 6, for instance, the arm 140A has started moving inwardly under the force of a fresh charge of high pressure steam (horizontal section lines) admitted into the high pressure chamber HP At the same time, the inward movement of the arm 140A opens the exhaust port A and allows a spent charge of steam (phantom section lines) in the low pressure chamber 151% to be exhausted through port 190A. Similarly, FIG. 6 illustrates a charge of steam (angled section lines) being transferred at the same time from the high pressure chamber I-IP to the low pressure chamber LP, as a result of the outward movement of the arm 140C. A residue of a steam charge (vertical section lines) from a previous cycle is also shown in FIG. 6 as it exhausts from chamber LP through the opened port 190C.

Engine operating parameters for the compound engine 100 having a rotor chamber with a four inch width and a 7.5 inch internal diameter, and having the rotor shaped as generally shown in FIGS. 3 and 4, were put into a computer programed to calculate the expected 17 engine performance. In one computerized example, charges of steam were introduced into the high pressure chamber HP at 200 psig, and the valve mecha nism 179 was arranged to cut off the steam after 1 of rotor rotation. The high pressure steam expanded within the high pressure chambers until the rotor rotated to 120, at which point the steam pressure was projected as being 198 psig. As the rotor continued to rotate from 120 to 2 10, the steam charges were transferred to the associated low pressure chambers LE without the work being done on or by the fluid. The steam then continued to expand in the low pressure chambers until the rotor had reached a position of 255. At this point, the exhaust ports l90A-C begin to open and the charges of steam in the low pressure chamber were exhausted from the engine. The projected pressure of the steam in the low pressure chamber at exhaust was 97 psig. The projected characteristics for a compound engine operating under these conditions were a mean torque output of 3,732 inch pounds with an output of 71 indicated horsepower at 1,200 rpm.

In another computerized example, the same compound engine was analyzed when' steam was admitted into the high pressure chambers at 200 vpsig, with the cutoff set at 55 of rotor rotation. Again, the steam expanded in the high pressure chambers until 120 of rotation of the rotor, at which point the steam pressure was projected as being 135 psig. The charges of steam were then transferred, without any work, to the associated low pressure chambers as the rotor rotated from a 120 position to a 210 position. From that point the steam expanded in the low pressure chambers until the rotor had rotated to a 255 position. The steam was then exhausted through the associated exhause port at 64 psig. The projected characteristics for this engine were a mean torque of 3,196 inch pounds, with a power output of approximately 61' indicated horsepower at 1,200 rpm.

Computerized data established that the operating characteristics of the compound engine 100 also are directly proportional to the rotor width and speed and the pressure of the incoming charge of external working fluid. Thus, the physical dimensions and the operating parameters of the engine, as well as the shape of the rotor 150, can be varied to suit particular engine applications.

SWITCHABLE ENGINE SlNGLE-LOBE ROTOR FIGS. 7 and 8 illustrate an engine 200 incorporating the features of the present invention which is adapted to be switched between a simple and a compound mode of operation. The switchable engine 200 thereby com-, bines the structural and functional features of the compound and simple engine in a single unit. Since it is switchable, the engine 200 can be operated as a simple engine when the engine application requires a relatively low-speed and high-torque output, such as when a vehicle including the engine is accelerating or climbing a steep hill. In the alternative, the engine 200 can be switched, either manually or automatically, to a compound mode of operation when the application requires high speed preformance with substantial fuel economy, such as when a vehicle is cruising at turnpike speeds.

The basic construction of the engine 200 is the same as the compound engine 100 described in detail above with reference to FIGS.-36. Both of the illustrated engines and 200, for example, incorporate a singlelobe rotor 150. Accordingly, the common components of the engines 100 and 200 have been given the same reference numerals in FIGS. 7 and 8. The essential difference between the switchable engine 200 and the above-described compound engine 100 is that the valve housing 170 of the engine 100 has been replaced by a modified valve housing 170'. In accordance with this invention, the valve housing 170' includes additional transfer channels and transfer vavles which allow the engine 200 to be operated as either a simple or compound engine.

. Referring to FIGS. 7 and 8 in more detail, the valve housing 170 of the engine 200 includes the compound",transfer channels .194AC connecting each of the high pressure chambers HP to the low pressure chambers LP associated with the adjacent arm A-C. As described above with reference to the engine 100, these transfer channels 194A-C permit the engine 200 to operate as a compound engine by compounding the expansion of a single charge of steam. In addition, the valve housing on the engine 200 includes simple transfer channels which bring each high pressure chamber HP into fluid communication with the low pressure chamber LP adjacent the same arm l40A-C. More specifically, a simple transfer channel 202A is provided to join the high pressure chamber HR, to the low pressure chamber LP,,; a simple transfer channel 2028 is provided to join the high pressure chamber HP with the low pressure chamber LP and a simple transfer channel 202C is provided to join the chambers HP and LP The valve housing 170 also includes standard threeway transfer valves 204AC arranged adjacent each of the low pressure chambers LP,, The transfer valves 204AC are in fluid communication with the compound transfer channels 19,4A-C and the simple channels 202AC which lead to the adjacent low pressure chamber LP and can be operated manually or automatically to control the mode of operation of the engine. When the valves 204AC are set into a first position, the low pressure chambers LP, are in fluid communication only with the compound transfer channels l94A-C, and the engine 200 will operate as a compound engine. Alternatively, movement of the transfer valves 204AC to a second position places the low pressure chambers LP in fluid communication with the simple transfer chambers 202A-C only. The engine 200 then operates as a simple engine.

The operating cycle for the engine 200 as a compound engine is the sameas .the above-described cycle of the compound engine 100 (FIGS. 36). The transfer valves 204AC bring the low pressure chambers LP ,Q into communication only with the associated compound transfer channels 194A-C, so that the charges of high pressure steam will be transferred to the low pressure chamber LP of the adjacent arm after the charges have expanded in the high pressure chambers I-IP Further, the projected performance characteristics for the engine 200, when operating as a compound engine, are essentially the same as projected for the compound engine 100.

The cycle of operation for the switchable engine 200 as asimple engine is schematicallyillustrated in FIG. 8. The transfer valves 204AC are adjusted to cut off the compound transfer channels 194AC from the associated low pressure chambers LP and to connect the low pressure chambers with the simple transfer channels 202AC. The channels 202A-C in turn bring the low pressure chambers LP into direct fluid communication with the high pressure chamber HP associated with the same arm 140A-C. Specifically, under these conditions the transfer valve 204A connects the chamber l-IP directly with the chamber LP,,; the valve 2048 brings the chamber l-IP into direct fluid communication with the chamber LP and the valve 204C brings the chamber l-IP into direct communication with the chamber LP As illustrated in FIG. 8, the transfer valves 204A-C, when set for the simple mode of operation, cause the initial charge of high pressure steam admitted through the valve 177 to be fed simultaneously into both the high and low pressure chambers associated with the same arm 140A-C. For example, the high pressure steam admitted through the steam chest 174A into the chamber HP A simultaneously fills the transfer channel 202A and feeds into the low pressure chamber LP,,. The horn 148 on the arm 140A seals the low pressure chamber LP from the high pressure chamber HP,,. The single charge of steam thus will expand in both chambers simultaneously, with the steam expanding in the chamber LP A working against the arm contact surface 149 and the steam expanding in the chamber HP working against the arm 140A and horn 148. The high pressure steam thereby expands against a substantial area of the associated arm 140A and imparts a high torque force to the rotor 150.

The additional transfer valves 204B and 204C operate in the same manner to direct a charge of high pressure steam into the high and low pressure chambers associated with the arms 1408 and 140C, respectively, at a selected time during the engine operating cycle. The sequential movement of the arms 140A-C and the resulting rotation of the rotor 150 which occur when the switchable engine 200 is operated as a simple engine are the same as described above with respect to the simple engine 10. To exhaust the spent steam charges through the ports 190A-C, the steam in the high pressure chamber HP, first is forced through the channel 202A-C into the associated low pressure chamber LP by the outward motion of the arms 140A-C. The entire steam charge will then exhaust through the port 190 of the adjacent arm. For example, the outward movement of the arm 140A in FIG. 8 will force the spent steam from the chamber l-IP through the transfer channel 202A and into the low pressure chamber LP,,, and the steam is then exhausted through the opened exhaust port 190B.

FIG. 8 schematically illustrates the relationship of the arms 140A-C when the engine 200 is operated as a simple engine. In FIG. 8, a charge of high pressure steam (horizontal section lines) is shown as expanding against the arm 140A within the chambers HR, and LP,, simultaneously, to thereby impart a substantial torque force to the rotor 150. The second arm 140B has completed its operating cycle and is maintained in its outermost position by the rotor 150 as the preceding arm 140A is moving inwardly from the force of the steam charge. A residual charge of spent steam (vertical section lines), remaining after the operation of the arm 140B, is shown as exhausting from the chamber LP through the adjacent exhaust port 190C. In addition, the third arm 140C, as illustrated in FIG. 8, has completed its inward power stroke and has started its outward movement. The expanded steam charge (angled section lines) in the chambers l-IP and LP associated with the arm 140C is in the process of being exhausted from the chamber LP through the opened exhaust port 190A. To accomplish this exhausting process the steam within the chamber l-IP is forced into the chamber LP through the channel 202C by the outward movement of arm 140C. Then, the entire charge of spent steam associated with the arm 140C will be exhausted through the port 190A by the rotation of the rotor 150 and the inward movement of the adjacent arm 140A.

The high torque characteristics of the switchable engine 200, when operating as a simple engine, are very similar to the characteristics of the above-described simple engine 10. The similarlity between the operating characteristics of these two simple engine embodiments results mainly from the fact that the effective area of the arms 140A-C contacted by the expanding high pressure steam is approximately the same in both engine embodiments. The projected performance of the engine 200 as a simple engine is illustrated by the following computerized analysis of an engine having a rotor chamber with a four inch width and a 7.5 inch internal diameter, and having a rotor shaped as generally shown in FIG. 8.

In one computer example, the engine 200 was operated as a simple engine so that the pressure of the steam fed into the high and low pressure chambers of each arm was 200 psig. The steam cutoff was selected to occur in each segment of the engine after the rotor had traveled through and the steam was allowed to expand through of rotor rotation to provide an overlap in the power impulses from the adjacent engine sections. The computerized data projected that under these conditions the steam pressure would drop to 198 psig after expansion through the 130 rotor rotation. The projected mean output torque for the engine was 6420 inch pounds, with a resultant power output of 122 indicated horsepower at 1200 rpm.

In a second computerized example, the same switchable engine 200 was operated as a simple engine with a 200 psig steam being admitted to the high and low pressure chambers simultaneously, with the steam cutoff adjusted to occur at 55 degrees of rotor rotation. The steam was allowed to expand for an additional 75 of rotor rotation, until the rotor rotated through a total of 130. The steam was finally exhausted at a pressure of 89 psig. The projected characteristics for such an engine were a mean output torque of 5434 inch pounds, with a resultant power of 104 indicated horsepower at 1200 rpm.

SIMPLE ENGINE DOUBLE-LOBE ROTOR FIGS. 9-11 illustrate a single engine unit 400 embodying the features of the present invention which incorporates six uniformly spaced swinging abutment arms 440A-F and a double-lobe rotor 450. The unit 400 is particularly adapted for a simple mode of operation with a pressurized working fluid, such as carbon dioxide or superheated steam. The engine 400 is a balanced unit which is very simple in construction. Moreover, the positioning and operation of the rotor and arms eliminate dead spots in the engine by providing for an overlapping of the power strokes or impulses transmitted to the rotor.

The double-lobe rotor 450 is positioned within a generally cylindrical rotor housing 420 on a central drive shaft 430. A key 451 or the like connects the rotor 450 to the shaft 430 in a manner which permits the rotor to 

1. A movable power arm for use in transmitting a torgue force to a rotor of a rotary engine contained within a sealed engine having substantial parallel housing side walls comprising: an elongate arm section having front and rear ends, substantially parallel side portions and substantial transverse top and bottom walls, with said bottom wall adapted for receiving a power impulse from a working fluid within the engine housing and with said side portions adapted to slide in close proximity to said housing side walls; connecting means intermediate said ends of said arm section for pivotally mounting said section in the engine housing adjacent the rotor and permitting said arm to swing inwardly against said rotor from an outward position adjacent said housing; a contact surface defined adjacent said front end of said arm section for engaging with and transmitting a torque force to the rotor; a sliding valve portion defined by the side portions adjacent said rear end of sadi arm section and having a predetermined configuration extending a substantial distance rearwardly of said connecting means and adapted to open and close exhaust port means in the adjacent portion of the engine housing side wall in response to swinging movement of said arm section about said connection means with sAid valve portions closing said exhaust port means when said arms are in said outward position; and sealing means providing along said side portions of said arm section for sealing with the engine housing to thereby prevent the flow of working fluid past said arm section within said housing.
 2. A power arm in accordance with claim 1 wherein said sealing means comprises a plurality of discontinuous labyrinth grooves provided in said side portions of said arm section.
 3. A power arm in accordance with claim 1 wherein said arm section includes a horn portion having substantially the same transverse extent as said arm section and projecting from said bottom wall of said section, said horn portion having front and rear edges which converge away from said arm section to provide said horn portion with a tapered configuration, with said front horn edge being arcuate and substantially concentric with said connection means so that said horn portion is adaped to seal against the engine housing as said arm swings about said connecting means and said horn and housing will cooperate to define an expandable fluid chamber.
 4. A rotary externally pressurized fluid engine comprising: a housing defining a generally cylindrical rotor chamber having and walls; a double-lobe rotor mounted on a shaft within said rotor chamber and having a substantial transverse surface and side portions spaced adjacent said end walls; six elongate arms extended around the inner periphery of said housing and spaced uniformly with respect to said rotor, each of said arms having side portions spaced adjacent said end walls and further having one end pivoted to said housing and the other end free to swing between an outward position engaged with said housing periphery and an inward position engaged with said rotor surface; said rotor surface including diametrically opposed first rotor segments sequentially engageable with the free ends of pairs of opposed arms as said rotor rotates in said rotor chamber to permit the engaged pair of arms to move inwardly and transmit a torque force to said rotor and shaft, a pair of diametrically opposed second rotor segments sequentially engageable with the free end of pairs of opposed arms to return the engaged pair of arms outward as the rotor continues to rotate; opposed inner dwell rotor segements positioned between said first and second segments and engageable with a pair of opposed arms to define the innermost position for said arms, and opposed outer dwell rotor segments between said first and second segments and engageable with a pair of opposed arms to maintain said arms in said outward position as said rotor rotates through a selected arc; expandable fluid chamber means defined between said housing periphery and each of said arms; valve means to sequentially direct charges of externally pressurized working fluid into said fluid chamber means adjacent a pair of opposed arms when said first rotor segments are positioned adjacent the free ends of said opposed arms so that said fluid charges operate into said rotor chamber against said opposed arms and the exposed portions of said rotor surface to thereby impart a double power stroke to said rotor and said shaft; exhaust means in fluid communication with each of said fluid chamber means and arranged to exhaust the charges from said rotor chamber; and means sealing said side portions of said rotor and said arms with respect to said housing end walls.
 5. A rotary engine in accordance with claim 4 wherein said arm and rotor are free to slide transversely within said rotor chamber and said sealing means for said rotor and arms comprises a plurality of discontinuous labyrinth grooves provided in said side portions of said rotor and arms.
 6. A totary engine in accordance with claim 4 wherein said first and second rotor segments are adapted to engage with a pair of opposed arms to move said same inwardly and outwardly, respectively, with substantially simplE harmonic motion.
 7. A rotary engine in accordance with claim 4 wherein said inner dwell segements on said rotor are adapted to engage a first pair of opposed arms as said first segments engage with a second pair of opposed arms for a selected degree of rotor rotation before said second rotor segments drive said first pair of arms outward, to thereby overlap the inward power strokes imparted to said rotor.
 8. In a power system having a source of externally pressurized working fluid, and outlet means for directing pressurized fluid from said source, the improvement comprising a rotary engine driven by said externally pressurized working fluid, and engine comprising: a housing defining a generally cylindrical rotor chamber having end walls; a double-lobe rotor mounted on a shaft within said rotor chamber and having a substantial transverse surface and side portions spaced adjacent said end walls; six elongate arms extended around the inner periphery of said housing and spaced uniformly with respect to said rotor, each of said arms having side portions spaced adjacent said end walls and further having one end pivoted to said housing and the other end free to swing between an outward position engaged with said housing periphery and inward position engaged with said rotor surface; said rotor surface including diametrically opposed first rotor segments sequentially engageable with the free ends of pairs of opposed arms as said rotor rotates in said rotor chamber to permit the engaged pair of arms to move inwardly and transmit a torque force to said rotor and shaft, a pair of diametrically opposed second rotor segements sequentially engageable with the free ends of pairs of opposed arms to return the engaged pair of arms outward as the rotor continues to rotate; opposed inner dwell rotor segments positioned between said first and second segments and engageable with a pair of opposed arms to define the innermost position for said arms, and opposed outer dwell rotor segments between said first and second segments and engageable with a pair of opposed arms to maintain said arms in said outward position as said rotor rotates through a selected arc; an expandable fluid chamber defined between said housing periphery and each of said arms; valve means to sequentially direct charge of externally pressurized working fluid into said fluid chamber adjacent a pair of opposed arms when said first rotor segments are positions adjacent the free ends of said opposed arms so that said fluid charges operate said rotor chamber against said opposed arms and the exposed portions of said rotor surface to thereby impart a double power stroke to said rotor and said shaft; exhaust means in fluid communication with each of said fluid chambers and arranged to exhaust the charges from said rotor chamber; and means sealing said side portions of said rotor and said arms with respect to said housing end walls.
 9. The power system in accordance with claim 8 wherein said pressurized working fluid comprises compressed gas.
 10. A power system in accordance with claim 8 wherein each of said engine arms includes a tapered horn member adjacent the free end thereof and projecting outwardly toward said rotor housing with each horn member having outwardly converging edges, and said rotor housing including horn recesses to receive said horn members, and wherein one of said horn edges slides in sealing engagement with said housing as said arms swing outward.
 11. The power system in accordance with claim 8 wherein said source of working fluid comprises a vapor generator and wherein said pressurized working fluid comprises vapor.
 12. The power system in accordance with claim 7 wherein said pressurized working fluid comprises superheated vapor.
 13. A rotary externally pressurized fluid engine comprising: a housing defining a generally cylindrical rotor chamber having end walls; a double-lobe rotor mounted on a shaft within said roTor chamber and having a substantial transverse surface and side portions spaced adjacent said end walls; six elongate arms extended around the inner periphery of said housing and spaced uniformly with respect to said rotor, each of said arms having side portions spaced adjacent said end walls and further having one end pivoted to said housing and the other end free to swing between an outward position engaged with said housing periphery and an inward position engaged with said rotor surface; said rotor surface including diametrically opposed first segments sequentially engageable with the free ends of pairs of opposed arms as said rotor rotates in said rotor chamber to permit the engaged pair of arms to move inwardly and transmit a torque force to said rotor and shaft, said rotor surface further including a pair of diametrically opposed second segments sequentially engageable with the free end of pairs of opposed arms to return the engaged pair of arms outward as the rotor continues to rotate; expandable fluid chamber means defined between said housing periphery and each of said arms; valve means to sequentially direct charges of externally pressurized working fluid into said fluid chamber means adjacent a pair of opposed arms when said first rotor segments are positioned adjacent the free ends of said opposed arms so that said fluid charges operate into said rotor chamber against said opposed arms and the exposed portions of said rotor surface to thereby impart a double power stroke to said rotor and said shaft; exhaust means in fluid communication with each of said fluid chamber means and arranged to exhaust the charges from said rotor chamber; said exhaust means comprising exhaust ports provided in said housing adjacent each of said arms and moting valve portions provided on said arms, said ports being arranged to be closed by said valve portions when the adjacent arm is in its outward position and opened into fluid communication with said rotor chamber when said adjacent arm swings a predetermined distance inward; and means sealing said side portions of said rotor and said arms with respect to said housing end walls.
 14. In a power system having a source of externally pressurized working fluid, and outlet means for directing pressurized fluid from said source, the improvement comprising a rotary engine driven by said externally pressurized working fluid, said engine comprising: a housing defining a generally cylindrical rotor chamber having end walls; a double-lobe rotor mounted on a shaft within said rotor chamber and having a substantial transverse surface and side portions spaced adjacent said end walls; six elongate arms extended around the inner periphery of said housing and spaced uniformly with respect to said rotor, each of said arms having side portions spaced adjacent said end walls and further having one end pivoted to said housing and the other end free to swing between an outward position engaged with said housing periphery and an inward position engaged with said rotor surface; a tapered horn member included on each arm adjacent the free end thereof and projecting outwardly toward said rotor housing with each horn member having outwardly converging edges; a horn recess provided in said rotor housing adjacent each arm to receive the associated tapered horn member, with one of said horn edges arranged to slide in sealing engagement with said housing as said arm swings outwardly; said rotor surface including diametrically opposed first segments sequentially engageable with the free ends of pairs of opposed arms as said rotor rotates in said rotor chamber to permit the engaged pair of arms to move inwardly and transmit a torque force to said rotor and shaft, said rotor surface further including a pair of diametrically opposed second segments sequentially engageable with the free ends of pairs of opposed arms to return the engaged pair of arms outward as the rotor continues to rotate; fluiD chamber means adjacent each of said arms comprising a first expandable fluid chamber defined by said housing, said rotor and the adjacent free ends of each of said arms, and a second expandable fluid chamber defined by said horn recesses and the adjacent arms and sealed from said first chambers by said arm horn members; valve means to sequentially direct charge of externally pressurized working fluid into said fluid chambers adjacent a pair of opposed arms when said first rotor segments are positioned adjacent the free ends of said opposed arms so that said fluid charges operate said rotor chamber against said opposed arms and the exposed portions of said rotor surface to thereby impart a double power stroke to said rotor and said shaft; exhaust means in fluid communication with each of said fluid chambers and arranged to exhaust the charges from said rotor chamber; and means sealing said side portions of said rotor and said arms with respect to said housing end walls.
 15. A rotary engine in accordance with claim 11 wherein said engine includes conduit means connecting each first chamber to the second chamber associated with the same arm so that said charges of working fluid operate in said connected first and second chambers simultaneously and said engine operates as a simple engine.
 16. A rotary engine in accordance with claim 15 wherein said engine further includes transfer channels connecting each second fluid chamber to the first fluid chamber associated with the preceding arm, and transfer valve means in fluid communication with said first chambers and selectively operable in one position to sequentially direct charges of said pressurized fluid into said chambers so that said charges operate simultaneously in the first and second chambers connected by said conduit means, to operate said engine as a simple engine; said transfer valve means being further operable in a second position to sequentially direct charges of said fluid into said second chambers for initial operation so that the following movement of said arms changes the volumes of the first and second chambers connected by said transfer channels and transfers said initial charges from said second chambers to said first chambers through said transfer channels, to permit said charges to operate further in said first chambers and thereby operate said engine as a compound engine.
 17. A rotary engine in accordance with claim 16 wherein said change in volume in the connected first and second chambers occurs at substantially the same rate so that the fluid charges are transferred from said second to said first chambers without performing substantial work on the fluid. 